Stephen Pair wrote:
Jimmie Houchin wrote:
I thought I saw something about image segments. Is there any information about that anywhere? I've tried to search the egroups archives but searching for "image" and "segments" isn't easy. :(
I can't point you to anything directly (other than the image itself). Perhaps Dan has a good description of them.
I thought (maybe naively so) that if image segments were possible that they would make for a great basis of an OODB. Reasoning that they are the native objects system of Squeak. If multiple Squeak image segments were usable from a master Squeak (and image) then one could partition apps and data into their own image segment. Just some thoughts. I may be late to this party. :)
I believe they can be the basis for a great OODB...however, the last time I looked, image segments specified a system of objects by identifying a set of "root objects" and then using the garbage collector to find all objects in the shadow of those roots. This is fine for certain applications, however, it is probably too slow for a database full of a bunch of really small ones. What's needed is a way of specifying the set of objects to go in an image segment in a more declarative way, avoiding the need to use GC...maybe this has been added recently? I don't think it should be too hard to do and would be really useful.
What I had in mind was very much an explicit use of image segments for persistence of certain objects. For example in a web app the web app logic would be in the root image. This image would also contain any persistence not explicitly specified to other image segments. This would allow for the image segments to be used similarly to tables in a RDBMS. In many instances the objects stored would require little GC due to the nature of what is stored.
This would still require transaction machinery to be really useful. All in all I don't know that it would have any advantages over what you have created or are creating as described in your PDF. At least not in web apps which need to scale.
Jimmie Houchin
- Stephen